Steel



UNITED STATES PATENT OFFICE.

STEEL.

No Drawing.

To all whomit may concern:

Be it known that we, PETER MAGGREGOR, of Atterclifi'e Forge and Rolling Mills, Sheffield, England, manufacturer, and ARTHUR BALFOUR, of Dannemora Steel Works, Sheffield, England, steel manufacturer, have invented a certain new and Improved Steel, of which the following is a specification.

This invention relates to the manufacture of steel and has for its object to provide a steel composition particularly suitable for making, cutting and milling tools, and as a substitute forhigh speed steel.

Heretofore, it has been proposed to manufacture self hardening steel alloys and steel suitable for the manu acture of armor plates, projectiles, and the like articles requiring ve great toughness, containing 1 per cent. or l ess of carbon together with nickel and a. comparatively low percentage of chromium, for instance 5 per cent. or less.

The percentage composition of these chrome-nickel steels has varied considerably according to the purpose for which the steel was required, but we have not found any heretofore known composition of chromenickel steel altogether suitable for our purpose referred to above. We have therefore made an original investigation of this subject de 91.0020 and have methodically carried out a series of experiments with various compositions and grades of steel, in order to determine, within definable limits, a composition which imparts the desirable qualities to cutting and milling tools, and can be used with advantage as a substitute for high speed steel.

As a result of our investigation and experiments we have found that a chrome-carbon steel containing comparatively high percentages of carbon and chromium, from 1 to 6 per cent of nickel, and a small amount of manganese is the best suited for the said purpose.

A steel made in accordance with our invention may therefore be defined as containing from 1 to/7% per cent. of nickel, from Specification of Letters Patent.

Patented Apr. 19, 1921.

Application filed September 18, 1918. Serial No. 254,888.

1 to 3.5 per cent. of carbon, cent. of chromium, of manganese.

A sample of the new and improved steel made in accordance with our invention has the following approximate composition.

from 6 to 20 per and a small percentage Small quantities of one or more of the following metals, viz., tantalum, molybdenum, tungsten, vanadium, zirconium and uranium, may be added to the ingredients used in making our improved steel. For the purposes of this steel these metals are substantially equivalent. Another suitable metal is cobalt. As no generic term including these several metals is known, we will designate them rarer non-ferrous metals, which term will be understood as covering the metals thus specified, which have in common the quality of alloying with the described nickel-chromium-manganese highspeed steel to vary but not diminish its stated properties. For instance, anything up to about 2 per cent. of any of the above metals may be added, except that in the case of cobalt, we prefer to use only about 0.9 per cent. or less.

What we claim and desire to secure by Letters Patent is 1. An improved steel suitable for cutting and milling tools and as a substitute for high speed steel, containing from 1 to 6 per cent. of nickel, from 1 to 3.5 per cent. of carbon, from 7% to 20 per cent. of chromium, and from 0.25 to 1 per cent. of manganese.

2. A steel of the composition of claim 1 plus not over about 2 per cent. of one of the. specified rarer non-ferrous metals.

3. An improved steel for the purposes set forth containing approximately, carbon, 1.45 5 per cent., silicon, 0.40 per cent., manganese,

0.25 per cent., sulfur, 0.03 pet cent., phosphorus, 0.03 er cent, chromium, 12.50 per cent., and nic e1, 3.50 per cent 4. A steel of the composition of claim 3 plus not over about 2 per cent. of one of 10 the specified rarer non-ferrous metals.

In testimony whereof we have signed our names to this specification.

PETER MACGREGOR. ARTHUR BALFOUR. 

